North Bay: Storm intensity affects sewer pipes, causes spills
POSTED: JAN 10 2019 06:50PM PST
VIDEO POSTED: JAN 10 2019 06:08PM PST
MARIN COUNTY, Calif. (KTVU) - A medium sized sewage spill in the North Bay has some officials thinking about not just replacing sewer pipes, but replacing them with bigger ones to account for climate change.
Downpours and intense storms called rain bombs are making sewer agencies think a lot more about current infrastructure.
Over the weekend, intense rains overwhelmed a bypass sewage pumping system as a contractor replaced an old, leaky pipe sending 100,000 gallons of raw sewage into the streets and storm drains of San Anselmo.
“A four million dollar capital project to enlarge the sewers in Ross Valley and San Anselmo and a storm came during our construction project,” said Ross Valley Sanitary District General Manager Steve Moore.
Moore said the intense weekend rains, almost four and a half inches, overwhelmed the bypass system.
“The bypass pumps and pipes were not large enough to convey the storm swollen waste water around the project. We had a couple of storms that were less than an inch, that it was able to send around the system,” said Mr. Moore.
Moore adds, while suction trucks were able to recover much spill, some went down curbside drains which flow into a creek which flows down to San Francisco Bay.
Though the neighbors support a better sewer system, the spill did not please them.
“None of he neighbors were notified that the was, in fact, first reported, 50,000 gallons of raw sewage. We have lots of kids, lots of children that come down and play in puddles here when it rains. I’m a nurse and it’s a health concern for most of us,” said neighbor Marianne Golden.
This work is being done for the district by a contractor, and while the contractor is responsible for the work, the district is still responsible for any pollution.
“We posted signs in areas where people might come into water contact in parks and along creeks to make sure that they don’t come into contact with that water,” said Moore.
Part of the design considerations for the much bigger pipes, is to account for for intense weather from climate change, weather that is speeding up the frequency of big storms the old pipe designers did not contemplate long ago.
“With climate change predictions, we’re seeing that the design storms were gutting outside of that range. We’ll have sudden, more intense events that dump more precipitation, rain, snow in the Sierras,” said Moore.
This district has 15 days to investigate and report findings to water quality officials who want to know if they should fine the district, the contractor, both or, possibly, no one. A bigger bypass system has been installed.